Proof. Let \( (x,t_r) \in \Omega _{\mu }\) .
It suffices to prove (), since (REF )
is proved as in the stationary context of Theorem
REF . We first recall a fundamental identity (E.10) [1]},
that is,
\(\Phi _{k+1}^{(j)}(\bar{\mu })=\mu _j \Phi _{k}^{(j)}(\bar{\mu })+\Psi _{k+1}(\bar{\mu }),\quad k=0,\ldots ,n, ~j=0,\ldots ,n.\) 
